[Problems]To provide a novel protease inhibitor and curative remedies and a therapeutic method for chronic obstructive pulmonary disease, immunodeficiency syndrome, alveolar proteinosis and circulatory diseases.[Means for Solving Problems]A protease inhibitor and a preventive or a remedy for chronic obstructive pulmonary disease or immunodeficiency syndrome characterized by containing at least one member selected from among redox active proteins and genes encoding the same and a preventive or a remedy for chronic obstructive pulmonary disease, alveolar proteinosis or circulatory diseases characterized by containing at least one member selected from IL-18 and a gene encoding the same.
